Just recently I bought an Act-Labs GS gun System on Ebay, and I thought it would be easy to use it with GS, 'cuz it's connected to the gameport and it works as a DirectInput device.
Well, as you might think, it was not easy. I tried to get the input from the guns via the joy_raw.x and joy_raw.y variables, I made an on-screen panel that displays the values of these variables, but it seems to be screwed up: the numbers that appear seem to be random (yes, I have calibrated the guns, and yes I did it for every screen resolution).
Did anyone of you get these babys to work? Is there a dll plugin for GS that makes it work?

I never had much luck with those guns except with the game that come with them.

I am currently working on a game that will use the Act-Labs lightgun, You program it as a mouse device not joystick, the lightbeam is the cursor and the trigger is left click. It is 3dgs compatible and there is a free SDK download here

http://www.act-labs.com/gun1.htm

look in the lower lefthand corner of the page.

The makers of the gun have visited this forum a few times trying to generate interest in developing games for the gun. I have been in contact with them (via email) and they will sell your game via their online store once it is done.

Obviously, you didn't get me right. I am using the Act-Labs GS Gun System, not the PC USB Lightgun. And this one works (or should work) as a joystick. But as it seems, there is no such dll, so I'll go and get the USB version. Really sad, 'cause I had planned to make a 2 player game.